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Biomedical subjects

M Stone

Publications and source records attributed to M Stone.

At least 91 records · Page 5Linked to original sources
PubMed1995

Preliminary study of the effect of aging following irradiation on the wear of ultrahigh-molecular-weight polyethylene.

Several studies have indicated that degradation of ultrahigh-molecular-weight polyethylene following gamma irradiation in air adversely affects the mechanical properties of the material; however, it is not known how this subsequently affects its wear rate. Wear studies have therefore been performed on three groups of ultrahigh-molecular-weight polyethylene; unirradiated material, recently irradiated material (aged for 2 months), and aged irradiated material (aged for 5 years). The aging took place in sterile packaging on the shelf. The wear studies were carried out on a tri-pin-on-disk wear tester, with a pin from each type of material being studied in each test. In each test the wear rate of the nonirradiated material was slightly lower than the 2-month-aged, irradiated material. The 5-year-aged, irradiated material had the highest wear rate, and this was significantly greater than that of the unirradiated material (P < .05).

Acetabulum↗
PubMed1995

Allogeneic transplantation combining mobilized blood and bone marrow in patients with refractory hematologic malignancies.

BACKGROUND: Mobilized blood stem cells have been used successfully in autologous transplant recipients to reduce the complications of pancytopenia due to dose-intensive chemotherapy. Reports of cytokine-mobilized blood progenitor cells in allogeneic transplant recipients are rare. STUDY DESIGN AND METHODS: This is a pilot trial of six patients. Patients with advanced hematologic malignancy received bone marrow (median total 2.6 x 10(8) mononuclear cells/kg) followed by four daily transfusions of blood (median total 9.5 x 10(8) mononuclear cells/kg) from HLA-matched sibling donors who were mobilized with recombinant human granulocyte-colony-stimulating factor (5 micrograms/kg/day subcutaneously for 5 days). All patients received cyclosporine and prednisone for graft-versus-host disease (GVHD) prophylaxis. RESULTS: An absolute neutrophil count greater than 500 per mm3 was achieved on Day 12, and platelet transfusion independence was achieved on Day 16. The median day of hospital discharge was Day 23 after transplant. All patients achieved 100-percent donor cell engraftment. Acute > or = Grade III GVHD did not develop in any patients, but all patients developed Grade I (n = 4) or Grade II (n = 2) acute GVHD. Chronic extensive GVHD developed in four of six patients. One patient died of pneumonia 263 days after transplant while undergoing immune-suppressive therapy for chronic GVHD. CONCLUSION: The transfusion of blood stem cells in patients undergoing allogeneic bone marrow transplant is well tolerated soon after transplant, but the development of chronic GVHD may limit the general usage of unmanipulated blood stem cells.

Adult↗
PubMed1995

A head and transducer support system for making ultrasound images of tongue/jaw movement.

A head and transducer support system (HATS) was developed for use in ultrasound imaging of tongue movement. Ultrasound is an imaging technique that captures tongue motion during speech and thus has great appeal as a tool for speech research. However, because ultrasound systems are designed for clinical use, the transducer is hand-held and it is almost impossible to hold it completely steady under the chin when collecting tongue data. A system was needed to fix the head and support the transducer under the chin in a known position without disturbing speech. The HATS system was designed, constructed, and modified to provide valid, reliable tongue movement data by (1) immobilizing the head and (2) positioning the ultrasound transducer in a known relationship to the head.

Head↗
PubMed1995

Experimental and theoretical study of the contact mechanics of five total knee joint replacements.

The tibio-femoral contact area in five current popular total knee joint replacements has been measured using pressure-sensitive film under a normal load of 2.5 kN and at several angles of flexion. The corresponding maximum contact pressure has been estimated from the measured contact areas and found to exceed the point at which plastic deformation is expected in the ultra-high molecular weight polyethylene (UHMWPE) component, particularly at flexion angles near 90 degrees. The measured contact area and the estimated maximum contact stress have been found to be similar in magnitude for all of the five knee joint replacements tested. A significant difference, however, has been found in maximum contact pressure predicted from linear elasticity analysis for the different knee joints. This indicates that varying amounts of plastic deformation occurred in the polyethylene component in the different knee designs. It is important to know the extent of damage as knees with large amounts of plastic deformation are more likely to suffer low cycle fatigue failure. It is therefore concluded that the measurement of contact areas alone can be misleading in the design of and deformation in total knee joint replacements. It is important to modify geometries to reduce the maximum contact stress as predicted from the linear elasticity analysis, to below the linear elastic limit of the plastic component.

Anthropometry↗
PubMed1994

Market work, wages, and men's health.

In this paper, we investigate the complex interrelations among work-time, wages, and health identified in the Grossman model of the demand for health. Hansen's generalized method of moments techniques are employed to estimate a 3-equation simultaneous model designed to capture the time dependent character of these interrelationships. We then estimate simpler models with more restrictive assumptions commonly found in the literature and find substantial differences between these estimates and those from our simultaneous model. For example, the positive relationship between work-time and health found in other studies disappears when the relevant simultaneities are taken into account.

Adult↗
PubMed1993

Neoadjuvant therapy for unresectable pancreatic adenocarcinoma.

The purposes of this study were to determine whether continuous infusion of fluorouracil combined with external-beam radiation therapy improved the resectability and survival of patients with pancreatic carcinoma. Sixteen patients with unresectable disease confined to the pancreas and celiac nodes were treated, and their outcome was compared with that of 24 patients with potentially resectable disease who were treated concurrently. The neoadjuvant therapy was completed with acceptably few toxic effects but with only a minor decrease in tumor size. Two patients underwent resection and remained free of disease 20 and 22.5 months later. However, the median survival of the entire neoadjuvant group was 8 months. All 24 patients with potentially resectable carcinoma underwent surgical exploration. Fifteen of the 24 patients underwent resection and survived a median of 12.5 months. Neoadjuvant chemoradiation may have improved outcome and resectability for two (12.5%) of 16 patients with unresectable pancreatic carcinoma, but more effective therapy options must be developed to improve outcome.

Adenocarcinoma↗
PubMed1993

Is liver transplantation indicated for cholangiocarcinoma?

Liver transplantation for unresectable primary liver cancer has met with skepticism due to early aggressive recurrences occurring in early series from many centers. The primary tumors for which transplantation has been performed have been hepatocellular carcinoma and cholangiocarcinoma. In an attempt to improve these poor results, we instituted a protocol with adjuvant chemotherapy and radiotherapy after liver transplantation for cholangiocarcinoma. Between December 1984 and December 1992, 701 patients underwent 795 liver transplants. Seventeen patients had a diagnosis of cholangiocarcinoma and form the basis of this review. Three patients were excluded from the study, two because of early postoperative deaths, and one because of an unknown bony metastasis present at the time of transplant. Eleven patients have experienced a recurrence, and 7 of these died secondary to their recurrence. Three patients are alive with no evidence of disease 44 months, 31 months, and 28 months, respectively, after transplant. The 1-year survival rate in these patients is 53%, and the disease-free survival rate is 40%. Patients were able to tolerate the adjuvant chemotherapy and radiotherapy without apparent morbidity or mortality. Unfortunately, this protocol does not appear to provide significant benefit. Until a better adjuvant therapy protocol is developed, it is questionable whether unresectable cholangiocarcinoma should be considered an indication for liver transplantation.

Chemotherapy, Adjuvant↗
PubMed1993

A case of spontaneous resolution of nonimmune hydrops fetalis.

Spontaneous intrauterine resolution of severe nonimmune hydrops fetalis has been rarely reported in the literature. A case of severe fetal hemolytic anaemia with hydrops fetalis but subsequent spontaneous resolution is reported along with a discussion of possible aetiologies.

Adolescent↗
PubMed1992

Automated detection of the tongue surface in sequences of ultrasound images.

An image processing system has been developed for a Macintosh II personal computer. It is designed to process sequences of sagittal tongue sections that are digitized in real time and stored in standard tagged image file format (TIFF). The successive processing steps are: (a) a low-pass filter for noise reduction, (b) a resampling of the sector of interest in polar coordinates, (c) a matched filter (vertical differentiator) for the enhancement of the tissue/air interface in the surface region of the tongue, and (d) an extraction of border points by searching for an optimal radial path along the angular dimension. This latter task is achieved by dynamic programming, which has the following advantages. First, due to the use of a global criterion to guide the detection, it is very robust. Second, as a result of certain restrictions of the allowable transitions, the extracted contours are smooth. Finally, the method permits the specification of particular predefined contour points. This system was implemented in a program that can handle image sequences in a fully automatic mode. Results obtained using ultrasound data are presented.

Humans↗
PubMed1991

Phase I immunotoxin trial in patients with B-cell lymphoma.

Fifteen patients with refractory B-cell lymphoma were treated in a Phase I dose escalation clinical trial with a highly potent immunotoxin consisting of the Fab' fragment of a monoclonal anti-CD22 antibody (RFB4) coupled to chemically deglycosylated ricin A chain. All patients had low, intermediate, or high grade non-Hodgkin's lymphoma. The immunotoxin was administered i.v. in two to six doses at 48-h intervals. The peak serum concentration and the t1/2 were not dose dependent among patients and averaged 1.3 micrograms/ml and 86 min, respectively. Three patients made antibody against A chain, and a fourth made antibody against both A chain and mouse immunoglobulin. Antibody responses were low (less than or equal to 85 micrograms/ml) in three patients and were not detected until 1 mo after treatment. The maximum tolerated dose of the immunotoxin was 75 mg/m2. Dose-related toxicities included vascular leak syndrome, fever, anorexia, and myalgia. Dose-limiting toxicities included pulmonary edema and/or effusion, expressive aphasia, and rhabdomyolysis (resulting in reversible kidney failure). There was no evidence of liver dysfunction. Partial responses were achieved in 38% of evaluable patients, and in those patients who had greater than 50% CD22+ tumor cells, 50% of the patients achieved a partial response. Clinical responses were not related to tumor grade and were generally transient, lasting between 1 and 4 mo.

Adult↗